The present invention relates in general to an improved rotary dispensing mechanism, and in particular to an improved rotary mechanism for automatically dispensing and retracting a cord-like element. Still more particularly, the present invention relates to an automated rotary mechanism for dispensing and retracting a cord-like element from a reservoir thereof.
Flexible line vegetation trimmers are known in the art, and are generally comprised of a long handle or rod having a cutting head at one end. The cutting head contains a spool of cutting line, similar to fishing line (polymeric monofilament), and a rotary device which causes the free end of the line to move in a circular fashion at high speed. When the cutting head is placed near overgrown vegetation, the spinning line hits the stalks or leaves and effectively cuts them away from the remainder of the plant. Flexible line vegetation trimmers have grown into a world-wide industry with annual sales exceeding a billion dollars.
One problem that has persisted with the use of flexible line trimmers (also referred to as rotary flails), is the dispensing of the cutting line from the spool. This line is typically constructed of a polymeric material that is relatively tough and durable but, after repeated use as a vegetation trimmer (or misuse on inappropriate surfaces), the line will break near the distal end, i.e., shortening the effective length of the line, and thus requiring replacement of the line, or extension of further line material from the spool.
In the prior art, there are four basic kinds of cutting heads: manual exchange; manual reel; semi-manual reel; and automatic reel. A manual exchange cutting head holds multiple lines which are not adjustable, but are instead completely removed and replaced when they get too short. The trimmer (rotary motor) must be stopped for replacement, and the stub ends are wasted. Additional material forming the mounting bracket for the lines is also discarded.
The reel types, whether manual, semi-automatic, or automatic, have a reel within a housing, and new line is delivered by releasing (rotating) this reel. With the manual reel type, the rotary motor must be stopped so the reel can be manually unlocked to extend new line. With the semi-automatic, feeding of new line is triggered by a hand lever or by bumping the cutting head on the ground. Manual and semi-automatic require the operator to monitor the line and decide when to take action. Another type of feeding device uses a mechanism which extends a length of line every time the rotary motor is slowed from a high operating speed.
The automatic reel types are equipped with a sensing device to monitor the line and activate a reel release or indexing mechanism to feed more line. A cycle of gradual decreases and sudden jumps in line length are an inherent feature because of the threshold for triggering the reel mechanism. Sudden jumps in line length cause wasted line, explaining the lack of commercial success of these types of cutting heads. Multiple independent automatic lines have been very impractical because of the complicated mechanisms involved. Today, almost all trimmers sold are equipped with bump feeds.
Reloading bump feeds is complicated and time-consuming. Casual users especially dislike the details of loading the line spool onto the cutting head. Even for those devices in which no disassembly or tools are required, it is still necessary to (i) bring the spool into loading alignment, (ii) insert the first cutting line into a loading hole, (iii) anchor the cutting line to the spool, (iv) repeat steps two and three for a second line, then (v) rotate the spool to draw the lines into the housing and wind them onto the spool. Bump feeds also have a tendency to jam. The bump button can get surrounded with mud, wet grass, or other bits of debris, and prevent proper dispensing of the line. Moreover, during feeding of a bump-type device, the head is subjected to sharp shocks which tend to jam the line in the coil and prevent smooth feeding of line. Clearing a jammed coil or bump button is time-consuming and can be further frustrating.
To date, rotary dispensing mechanism such as vegetation trimmers have only been capable of increasing the length of their consumable filament lines relative to the spool. Other than providing a sharp blade at a fixed distance from the spool for chopping off excess line, no vegetation trimmer is capable of reducing the length of the line without cutting the line and wasting the cut portion.
In addition, all vegetation trimmers dispense additional filament in such a manner that the cutting radius of the trimmer constantly varies. It has never been possible to maintain the filament at an ideal cutting length without cycling between upper and lower cutting radius bounds. This problem exists for all three types of filament feeding mechanisms (manual feed, semi-automatic feed, and automatic feed). Before additional filament is released, the cutting radius must be worn down or consumed to trigger a xe2x80x9crelease eventxe2x80x9d (e.g., the operator actuates a mechanism, or the machine deploys more line). Moreover, when a release event does occur, almost all such rotary devices release an excessive length of filament that must be wastefully cut off to a proper length before the device can be effectively used again. Furthermore, rotary devices that utilize automated filament feeders typically require elaborate mechanisms with complex moving parts that are more expensive and less reliable than their primitive counterparts.
Even relatively simple, automatic feeding mechanisms, such as the one disclosed in U.S. Pat. No. 4,569,134, require a significant reduction in the cutting radius before the mechanism will deploy additional filament. These devices typically have a spool with a pair of sidewalls that are joined at their peripheries by guide support rods. A length of filament is coiled on the spool for vegetation trimming. The free end of the filament (three free ends are shown) bends around one of the guide support rods before extending radially away from the spool. The guide support rods prevent the filament from being inadvertently released and are needed to prevent unintended release of the filament both during operation and during non-operation.
During operation, a substantial portion of the filament must be consumed before additional filament is released. Unfortunately, the cutting radius of the vegetation trimmer is concomitantly reduced, thereby reducing the effectiveness of the trimmer. only when the shortened filament approaches its supporting rod does the filament release from the rod to increase the cutting radius once again. Thus, this trimmer operates in a cycle with discrete unwinding events, triggered by a significant shortening of the extended line. The cutting radius fluctuates between upper and lower bounds, gradually decreasing, then suddenly increasing when a discrete unwinding event is triggered.
In light of the foregoing, it would be desirable to devise an improved method of dispensing cutting line in a vegetation trimmer. It would be particularly advantageous if the method utilized a cutting head that would rarely, if ever, jam nor need maintenance or adjustment, was easily reloaded without tools or requiring disassembly, and was capable of dispensing the cutting line from a reservoir.
A rotary device for automatically dispensing and retracting a line, such as cutting filament for a vegetation trimmer, has a spool around which is wound a small coil of the line. The line has a cutting segment that extends radially from the spool. The cutting segment has a precise length that is automatically maintained by a balance of centrifugal force and aerodynamic drag. The rotary device also has additional storage capacity for the line. An additional supply of line for the rotary device beyond the small coil may be stored in many different forms while remaining ready for immediate deployment and use. Examples include extended storage loops of the line protruding from the spool, a second coil or reservoir of line located remotely from the spool, or a magazine of the line mounted to the spool.
Accordingly, it is an object of the present invention to provide an improved rotary dispensing mechanism.
It is an additional object of the present invention to provide an improved rotary mechanism for automatically dispensing and retracting a cord-like element.
Still another object of the present invention is to provide an automated rotary mechanism for dispensing and retracting a cord-like element from a reservoir thereof.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.